Done with Rector (attributes sets for Symfony, Doctrine, Gedmo and Sensio):
Doctrine mapping (driver: attribute), routes, serializer groups, validation
constraints, Gedmo extensions, Sensio IsGranted/Security/ParamConverter
(still provided by SensioFrameworkExtraBundle for now).

Checked identical before/after: routes (debug:router), Doctrine, validator,
serializer and Gedmo metadata of every entity.